Circuit breaker having a compensating element which compensates for ambient temperature without displacing the catch attached thereto



3,361,882 COMPENSATES G Jan. 2, 1968 D. E. CLARKE CIRCUIT BREAKER HAVINGA COMPENSATING ELEMENT WHICH FOR AMBIENT TEMPERATURE WITHOUT DISPLACINTHE] CATCH ATTACHED THERETO Filed Oct. 24, 1965 5 Sheets-Sheet 5 a 2 4 0m a a Ill! X m 1| r N En M I m 4 llll I- H K x -1! 8 m 0 6 M 4 u 4% d J1\\ W$% Inventor; Dan 1?, Clarke, 5 J 2 4 Q M Aggy 3,361,882 COMPENSATESG Jan. 2, 1968 D. E CLARKE CIRCUIT BREAKER HAVING A COMPENSATING ELEMENTWHICH FOR AMBIENT TEMPERATURE WITHOUT DISPLACIN THE CATCH ATTACHEDTHERETO Filed Oct. 24, 1965 5 Sheets-Sheet 4 4 0 r! :J 0 a7? 4 6 ,t 27072827/ 2 0 6840 0 t /m a /Nm0 0 .m/ /MM mm mm A w i, w F n0 2 1 w M Wa M MM 6 M a Z I A Jan. 2, 1968 D. E. CLARKE 3,361,

CIRCUIT BREAKER HAVING A COMPENSATING ELEMENT WHICH COMPBNSATES FORAMBIENT TEMPERATURE WITHOUT DISPLACING THE CATCH ATTACHED THERETO FiledOct. 24, 1965 5 Sheets-Sheet 5 Inventor; David E Cla /rife, 9

United States Patent M CIRCUIT BREAKER HAVING A COMPENSATING ELEMENTWHICH COMPENSATES FOR AMBI- ENT TEMPERATURE WITHOUT DISPLACING THE CATCHATTACHED THERETO David E. Clarke, Attleboro, Mass., assignor to TexasInstruments Incorporated, Dallas, Tex., a corporation of Delaware FiledOct. 24, 1965, Ser. No. 504,632

Claims. (Cl. 200116) ABSTRACT OF THE DISCLOSURE A miniature, trip-free,ambient-compensated, circuit breaker is shown to comprise a base orhousing having first contact means fixedly mounted therein. A manualactuating means is mounted on the base for movement between first andsecond switch position and carries a first bell-crank latch rotatablymounted thereon, the latch carrying second contact means to be engagedand disengaged with the first contact means for making and breaking anelectrical circuit therethrough. A first thermostatic element blade ispivotably mounted within the base or housing so that the opposite end ofthe blade is free for movement and an elongated catch member is attachedat one end to said thermostatic blade adjacent the pivoting end thereof,the catch member having its opposite end disposed to normally engage thefirst latch during movement of the actuating means into the secondswitch position for rotating the first latch to engage the secondcontact means with the first contact means to close a circuit. A secondlatch holds the actuating means in said second position when the firstlatch is engaged with the catch, the second latch being releasable bymanual movement of the actuating means for permitting the actuatingmeans to move to the first switch position to disengage the first andsecond contact and to open the switch circuit. Current-responsive meansinterposed Within the switch circuit are mounted for movement on thebase in response to selected current in the switch circuit and motiontransfer means extend between the current responsive means and saidthermostatic blade to move the catch out of engagement with the firstlatch in response to selected current in the switch circuit forpermitting the actuating means to move to the first switch position toopen the switch circuit.

This invention relates to a new and improved circuit breaker, and moreparticularly to a new and improved circuit breaker of the thermostatictype for applications in which it is desired to interrupt an electricalcircuit under predetermined conditions. In circuit breakers, desiredfeatures are: the contacts are to open with a snap action the circuitbreaker, if thermostatically trippable, is ambient compensated; thedevice will indicate visually that it has tripped; calibration of thedevice is readily made; the circuit breaker can be manually actuated asa switch; and the device is tripfree. (By the expression trip-free ismeant a device which will open its contacts upon response to overloadcurrent passing through it, even though the manually actuable resettingmeans is held in the contact-closed position.) In addition to the above,it is also desirable to have a circuit breaker which is small in sizeand weight, is relatively economical to manufacture, and as to which itis possible to construct most of the operating features of the deviceoutside the casing which holds the same, this assembly then to beinserted in the casing as a final step prior to calibration of thedevice.

It is readily understandable that to provide all of the 7 above featuresof a circuit breaker in a small device is 3,361,882 Patented Jan. 2,1968 this invention to do so.

Among the several objects of the invention, therefore, may be noted theprovision of a new and improved snapacting circuit breaker for theprotection of electrical circuits and components against transients,sustained overloads and short circuits; the provision of a circuitbreaker of the class described which is trip-free; the provision of athermostatic circuit breaker which is ambient compen sated; theprovision of a circuit breaker which may be assembled as to many of itsconstruction features outside the casing prior to final assembly andcalibration, thus leading to economy and ease of assembly; the provisionof a circuit breaker of the classes described which indicates that thecircuit breaker has automatically tripped; the provision of a circuitbreaker which can be used as a manually operated switch Withoutdeleterious effects on its function of responding properly to overloads;the provision of a circuit breaker which is small and light weight; andfinally the provision of a circuit breaker which is economical tomanufacture and readily adapted to mass production means.

Other objects will be in pointed out hereinafter.

The invention accordingly comprises the elements and combinations ofelements, features of construction and arrangements of parts which willbe exemplified in the structures hereinafter described and the scope ofthe application of which will be indicated in the appended claims.

In the accompanying drawings in which several of the various possibleembodiments of the invention are illustrated:

FIG. 1 is an elevation, in section, of one embodiment of the invention;

FIG. 2 is a side elevation, embodiment;

FIG. 3 is a sectional view of FIG. 1, taken in the direction of sightlines 3-3 thereon;

FIG. 4 is a fragmentary section of a portion of the FIG. 1 embodiment;

FIG. 5 is a view corresponding to FIG. 1 but showing the device with itscontacts open;

FIG. 6 is a view similar to FIG. 1, but showing an intermediate positionof the operative parts;

FIG. 7 is a fragmentary sectional view of FIG. 6 taken in the directionof sight lines 77 thereon;

FIG. 8 is a sectional fragmentary view of a portion of the FIG. 1embodiment, taken in the direction of sight lines 8 8 on FIG. 6;

FIG. 9 is a plan view of one element of the FIG. 1 embodiment;

FIG. 10 is a sectional elevation of the FIG. 9 element, taken in thedirection of sight lines 10"10 thereon;

FIG. 11 is a side view of a terminal and contact structure of the FIG. 1embodiment;

FIG. 12 is a plan view of the FIG. 11 terminal and contact structure;

FIG. 13 is an elevation part apparent and in part in section, of theFIG. 1

of a combined mounting and adjusting bracket element of the FIG. 1embodiment;

FIG. 14 is an end view of the FIG. 13 element;

FIG. 15 is a cross section of the FIG. 13 element, taken in thedirection of sight lines 1515 on FIG. 13;

FIG. 16 is an end view of an assembly of the FIG. 13 element, astationary terminal, a thermostatic element, and a stationary contact,all as used in the FIG. 1 embodiment;

FIG. 17 is an elevation of the FIG. 16 assembly;

FIG. 18 is a cross section of the FIGS. 16 17 assembly, taken in thedirection of sight lines 1818 on FIG. 17;

FIG. 19 is an elevation of an assembly of a movable contact andsupporting contact arm of the FIG. 1 embodiment;

FIG. is a side elevation of the FIG. 19 embodiment;

FIG. 21 is a sectional view of the FIG. 19 assembly, taken in thedirection of sight lines 2121 thereon;

FIG. 22 is a perspective view of a bell-crank element of the FIG. 1embodiment;

FIG. 23 is a perspective view of another element of the FIG. 1embodiment;

FIG. 24 is a fragmentary section of an assembly (incorporating theelements of FIGS. 21-23) used in the FIG. 1 embodiment; and

FIG. is a fragmentary section of a device similar to FIG. 1 in manyrespects, but showing the details of another embodiment of theinvention.

The dimensions of certain of the parts as shown in the drawings may havebeen modified and/ or exaggerated for the purpose of clarity ofillustration.

Referring now to the drawings, and more particularly to FIGS. 1 and 2,one embodiment of this invention takes the form of thermostatic circuitbreaker generally indicated by reference numeral 2, and includes ahousing or casing 4 which may be made of any suitable molded resin whichis insulating and durable. Also, the resin should be arc-resistant, andan example thereof may be a phenolic resinous material. At one end ofthe casing suitable slots 6 and 8 are provided for receiving the fixedlymounted terminal structures 10 and 12. As shown, terminals 10 and 12 areof the screw-type, but if desired they may be of clinch-type, orsolder-type.

For ease of assembly of the circuit breaker into a complete device, thecasing 4 is made of two clamshells 14 and 16. In this construction,one-half of slots 6 and 8 each is molded in the respective clam shell,these slots matching when the clamshells are put together. When the clamshells are put together in final assembly they are held together byscrews or rivets passing through the properly provided holes 18 whichhave previously been molded in the respective clam-shells and whichmatch when the clam shells are assembled.

At the end of the clam-shells remote from the end of the slots 6 and 8,there is provided an inwardly projecting molded shoulder 20. Shoulder 20is received by recess 22 extending around the outer periphery of theneck structure 24 to hold neck 24 securely to the casing, the peripheralrecess 22 providing the engaging oppositelydisposed shoulders 26 and 28for this purpose.

It will be noted that in order to keep the neck 24 from turning in thecasing, as mounted, the oppositely-disposed flat portions 30 and 32 areprovided on shoulder 26, and a suitably molded recess 34 is provided inthe ends of the clam-shells which provides a matching depression toreceive the thus-shaped shoulder 26. Neck 24 is made of suitable metalsuch as steel.

Neck 24 comprises the mounting for a plunger assembly and mechanicallatch which will now be described, and which is one of the features ofthe invention.

Neck 24 is provided with a bore 36 at the outer end thereof, and bore 36communicates with bore 38 of larger diameter at the inner end thereof.Bores 36 and 38 are co-axial, and received in these bores is thecomposite plunger indicated generally by numeral 40 and comprising apush-button or head 42 and a cylindrical sleeve 44. Head 42 may be madeof electrically insulating molded resin and is provided with theco-axial bores 46, 48, 50, and 52. Sleeve 44 has one end 54 reduced indiameter, as shown, which end fits into bore 52. A screw 56 passesthrough bore 50 and into threaded engagement with a bore 58 provided inend 54 to fasten head 42 to sleeve 44. A cover cap 60 may thereafter bepress-fitted into bore 46 in order to prevent tampering with the screw56.

In order to be sure of proper clearance for the push button 42 in thebore 36, the end 62 of button 42 is slightly reduced in diameter asshown.

As indicated above, sleeve 44 is preferably made of steel, and in orderto prevent its turning in the neck 24,

a keyway 66 is milled in its outer surface, which keyway is adapted toreceive the key 64 which is provided as shown in the neck 24. In thisinstance, the key 64 has been provided by milling a slot at the outerend of the neck 24 in order to reduce the wall thickness of a portion ofthe neck, and then thekey 64 is formed by an upsetting operation so asto project inwardly into the keyway 66.

The inner end of sleeve 44 is provided with a peripheral shoulder 68 asshown to act as a bearing for a compression spring 70. Spring 70 is thebutton-return spring, and its other end has for its bearing a cup-shapedwasher 72 which is mounted by a suitable upsetting or staking operationat the end of sleeve 44. Washer 72 has a hole 74 through it, as shown,of suitable diameter to receive freely a latch-plunger 86 and certainassociated parts which will now be described.

Sleeve 44 is provided for a portion of its length with the bore 76.Located diametrically opposite each other are the two holes 78 and inthe wall of sleeve 44 each hole being adapted to receive slidable therespective ball bearings 82 and 84.

Slidably received in bore 76 is the latch plunger 86 which is likewisemade of steel and preferably hardened. The middle portion of latchplunger 86- is fashioned as shown in the form of a pair of coaxial coneswhose apices are joined. The size of plunger 86, the inward depth of thecones, the size of the holes 78 and 80 and the aforementioned ballbearings 82 and 84 are all so related that when the restraining forceupward on the latch plunger is relieved, as will be described later, theball bearings 82 and 84 are permitted to move toward each other asuflicient distance for the ball bearings to clear the shoulder 92formed at the juncture of bores 36 and 38.

At the inner end of plunger 86, there is provided the threaded stub 94which is suitably threaded into a connecting link 96 which is made of amolded, tough resin such as a phenolic resin or, for example, nylon. Ahole 98 (see FIG. 4) is provided through the end of connecting link 96,and a suitably dimensioned slot 100 is also provided at this same end toform a clevis or yoke. If desired, the stub 94 may be in the form of aheaded extension, and the connecting link 96 may thereafter be moldedabout the thus-formed stub for secure engagement to latch plunger 86.

It will he thus seen that with the above construction of the neck 24,sleeve 44, latch plunger 86, and the ball bearings 82 and 84, one of thefeatures of the invention is provided; namely, that a completemechanical latch is now positioned in the neck 24, and by thus utilizinghitherto unused space, miniaturization of the whole circuit breaker isfurthered. With the assembly thus described in the position shown inFIG. 1, then if the push button 42 and the end of the connecting link 96are squeezed together, the plunger assembly 40 is held relativelyimmovable in the neck 24 because of the latching engagement of the balls82 and 84 with the shoulder 92. However, if this pressure is released,and the plunger 86 is moved downwardly (as drawn), the balls 82 and 84are permitted to move toward each other in the recess provided by theinverted cones 88 and to clear the shoulder 92. This inturn permits thewhole plunger 40* assembly to move upwardly (as drawn) in the neck 24 toperform certain contact-opening operations.

Rotatably mounted in slot by means of a transversely extending pin 102is the bell crank or latch 104, the bell crank being provided with asuitable hole 106 for this purpose. Pin 102 passes through the hole 98,and for guiding purposes, the ends of pin 102 slide in slots 108 and 110suitably molded in the walls of the clam shells 14 and 16.

Bell crank or latch 104 is provided with a laterally extending latchpart 112 and, in angular relationship to latch part 112, an extendingleg 114 which is provided with a suitable hole 116 for engaging one endof the tension spring 117, the other end of spring 117 being attached toan extending finger 118 of anchor plate 119. Plate 119 is held in slot100' by means of the aforesaid pin 102 which passes through a hole 120in plate 119. The latter has provided thereon a flat side 121 which isso positioned with respect to hole 120, that when the plate is held inthe slot 100 by the pin, side 121 abuts the end of the slot so thatplate 119 cannot rotate about pin 102. Thus in effect, plate 119 is ameans for attaching the stationary end of spring 118 to the connectinglink 96 for biasing the bell crank 184 counterclockwise about pin 102.

Referring now to FIGS. 9 and 10, there is shown a composite catch thepurpose of which is to releasably engage the latch part 112 onbell-crank 104, and act as an ambient compensation means for thethermostatically operating portion of the circuit breaker.

The aforesaid combined catch and ambient compensation structurecomprises three parts; namely, the compensation element 122, the catchproper 124, and the leaf spring 126. Element 122 is made of thermostatmetal, is U-shaped, and has the legs 128 and 130. The catch 124 isT-shaped, as shown, having at one end the cross-bar 132. The ends of thelegs 128 and 131) are welded or otherwise tightly fastened to thecross-bar 132 as shown. Leaf spring 126 is welded or otherwise securelyfastened to the top of the catch 124, and projects somewhat above theend of the catch, as shown at numeral 134. Portion 134 acts as aback-stop for the latch part 112 of the bell crank to keep part 112 fromover-riding the catch.

In view of the fact that the bimetal compensating element 122 isfastened to the catch 124 only at the ends of the legs 128 and 130, itwill be seen that if the element 122 is heated, it can bend or curve byitself without affecting the position of the catch 124. That is, catch124 will not move when element 122 bends under the influence of atemperature change. As shown, the high expansion layer of the element122 is to the right as drawn, and the low expansion layer is to theleft. Thus, when the element 122 is heated by the surrounding ambient itwill flex or bend to the left, as drawn.

The bimetal compensating element 122, together with its associated catch124 and biasing spring 126, is pivotally mounted by its end in a pair ofslots or recesses 136 and 138 molded in the walls of the clam-shells 14and 16. Into these are pivotally fitted the respective ends of thecross-bar 132. As so mounted, the spring 126 bears against the side wallof the casing, and therefore biases the compensating element 122clockwise, as drawn, about its pivot point in the recesses 136 and 138.

Turning now to FIGS. 19-24, there is shown in detail the bell crank 104and its assembly with a movable contact structure. The bell crank isprovided with the contact leaf-spring receiving and holding recesses andshoulders 140, 142, and 144. A retaining hook portion 146 provided atthe outer periphery of the bell crank.

The movable contact 148 is bifurcated and 1n this 1nstance, is made ofbilayer material, the front surface 158 being of electrical contactmaterial such as silver, and the backing layer 152 being of a materialsuch as steel or nickel which is adapted to be readily welded to theleaf spring 158. As indicated, contact 148 is bifurcated to provide thelegs 154 and 156 for the purpose of making contact 148 a bridging typecontact. Spring 158 in this instance is shown as a leaf spring having areturn-bent portion 160. One end of spring 158 is bifurcated to providelegs which match the legs 154 and 156 of the movable contact 148. Thebight portion of spring 158 is also bifurcated as shown at numeral 162to provide greater flexibility of the spring, and to provide clearancefor inserting the spring in the ball crank 184.

Two notches 164 and 166 are also provided in the spring, notch 164 beingin the forepart of the spring and notch 166 being in the return-bentportion. At the lower end of notch 166, the material of return-bentportion 160 is formed inwardly to provide a projection 168 to assist inholding the spring in the bell crank 104.

In order to assemble the combination of the spring 158 and bell crank104, the ends of the spring are held together suflicient to slide thebell crank into the bifurcation at 162 and into the notches 164 and 166.In this position, these notches straddle the body portion of the bellcrank 104 to prevent too much lateral play. The insertion is done farenough so that when the ends of the spring are released, the free end ofthe return bent portion is engaged in the shoulder 144, and theprotrusion 168 comes to bear against one surface of the recess 142, allas shown. In this position, the hook portion 146 of the bell crank actsas a stop to prevent forward movement of the spring 158, and thecombination of hook 146, the protrusion 168, and the shoulder 144 serveto lock the spring and its movable contacts securely in place in thebell crank 104.

Turning now to FIG. 1, there is shown stationary contacts 178 and 172mounted in the base of the circuit breaker in fixed position. Contact170 is mounted on an extension of the terminal 10 by a suitablefastening means such as welding, or soldering, the complete structurebeing held in the casing by means of slots 6. Contact 172 is likewisemounted on a support 174, being fastened thereto by welding or solderingor other conventional means. Support means 174 is made of metal and isheld in the casing by means of a slot provided by the end wall of thebase and an interiorly positioned molded partition 176, the partitionand the end of the casing also providing an interior channel adapted toreceive an electrically connecting lead or strap 178. Connecting strap178 is electrically attached at one end to the support 174 and at itsother end is electrically attached to the end of leg 182 of thethermostatic bimetal actuator 188. Contacts 170 and 172 are thusseparate, and are adapted to be bridged by the bridging movable contact148 when contact 148 is in engagement therewith.

Referring now to FIGS. 13-17, a U-shaped thermostatic metal actuator 180is provided having the legs 182 and 184. The free ends of legs 182 and184 are connected, in a manner now to be described, to a channel-shapedsupporting member 186. In order to lessen the rigidity of the channelmember for purposes of calibration of the thermostatic bimetal actuator180, a bottom of the channel member is slotted as shown in order to haveone wall 188 of the channel supported from the other Wall 190 thereof byonly the center connecting strap or web 192. A tapped hole 194 isprovided in Wall 190, and an adjusting screw 196 is suitably providedtherein and extends to abut wall 188 for the purpose of spreading thewalls of the chan nel for calibration purposes.

Aflixed to one end of the channel is a bent over portion of the end ofleg 182 of thermostat actuator 180. The end of leg 182 is electricallyinsulated from the channel 186 by means of conventional insulation andinsulating washers 195, 197, and 198. Insulating material 197 extendsfar enough up the leg 182 to lie between the leg and wall 188, thuspreventing electrical contact between leg 182 and the channel at thispoint. Instead of continuing material 197 up the leg, a separate pieceof insulating material may be used, if desired.

Also fastened to this end of the channel is one end of the connectingstrap 178, and it will be noted that this end of strap 178 makeselectrical connection with the bent over end of leg 182. These severalparts are fastened together by conventional means such as the rivet 200.

A bent over portion of the free end of leg 184 is fastened directly tothe other end of channel 188 by means of welding (as shown) or, ifdesired, by riveting. This end of the thermostat actuator 180 istherefore in electrical connection with channel 186. As draw the highexpansion side of actuator 180 lies on the right and the low expansionside on the left.

By the above construction, it ing the adjusting screw 196 inwardly oroutwardly, the walls 188 and 190 of the channel are spread apart orpermitted to approach each other, and this motion of the wall will beseen that by turn- 188 has the effect of causing the thermostat actuator180 to move toward or away from the bimetal compensating element 122.

Channel 186 is mounted by the web 182 to one end of the stationaryterminal 12 which in turn is securely mounted in a slot 8 in the ends ofthe clam shells 14 and 16 provided for that purpose. Terminal 12 may beattached to the center Web 192 by Welding or riveting, and is inelectrical connection therewith.

Provided in each of the opposing face walls of the clam shells 14 and 16are a pair of slots 202. Slots 202 receive in slidable relation theedges of slide member 204. Slide 204 is a generally rectangularly shapedpiece of molded electrically insulating material, such as a phenolicresin, and its purpose is to transmit motion from the thermostatactuator 180 to the compensating element 122, and thus to the catch 124.Slide 204 is provided with a suitably shaped and dimensioned hole 206through which is adapted to pass freely the connecting link 96 and itsassociated bell crank and movable contact.

It will be noted that with the above construction, electrical currentpasses through the circuit breaker via the path of terminal 12, channel186, leg 184, leg 182, connecting strap 178, support 174, electricalcontact 172, bridging contact 148, electrical contact 170, and terminal10. It will be noted also that the ambient compensating element 122 doesnot receive electrical current, and there fore derives its temperaturechange (if any) because of the temperature of the ambient airsurrounding it or by radiation from the casing itself, or conductionfrom heated portions of the casing.

In assembling the various parts of the device, the feature of having thebell crank spring 117 fastened to the latch plunger 86 will now becomeapparent. By doing this, many of the various elements of the device maybe assembled outside the casing as a unitized structure. That is, thepush button 42, sleeve 44, latch plunger 86, balls 82 and 84, neck 24,spring 70, connecting link 96, bell crank 104 with its associated spring158 and movable contact 148, and tension spring 118 may be so assembled.Slide 204 is also put in place on this assembly. In one-half of thecasing (for example, clam shell 16) can then be placed stationaryterminal and its contact 170. In the other clam shell 14, can be put theother stationary contact 172 and its supporting structure 174, thestationary terminal 12, the channel member 186, and the thermostatactuator 180. The above associated unitized structure (on which has nowbeen put slide 204) can then be put in place in such a position that thelatch 112 engages the catch 124, and then the other clam shell 16 (forexample) is fitted into proper enlignment. The two clam shells arethereafter fastened together to hold the assembly in place.

The operation of the device will now be described.

The position of the parts shown in FIG. 1 was arrived at by pushing theplunger inwardly into the casing. When this is done, the latch 112 iscaught by the catch 124 and bell crank 104 will rotate clockwise underthe influence of the pin 102 and against the pull of the tension spring118 to bring the movable contact 148 into engagement in bridging fashionwith stationary contacts 170 and 172.

Upon inward motion of the plunger 40, the balls 82 and 84 are pushedoutwardly by the lower cone 90 (as drawn) beyond the shoulder 92, andcompression spring 70 is compressed. When the plunger is now released,the cone 90 acts against the balls to maintain them in latchingengagement with shoulder 92. The latch plunger 86 is maintained in anoutwardly biased position because of the force against the pin 102 ofthe leaf spring 158 and spring 117, this force fulcruming on the latch112 and end of catch 124. If an overload current now flows through thecircuit breaker, thermostatic actuator 180 will heat because of thecurrent through it, and will bend to the left. As it bends to the left,it will thrust upon slide 204 and thus the motion of the thermostatactuator 180 will be transferred by slide 204 to the bimetalcompensating lever 122. Motion of the thermostat element 180 will thusmove lever 122 to the left carrying the catch 124 with it until thelatch 112 escapes the catch. (See FIG. 6.) With the loss of the fulcrumfor the aforesaid reactive force (caused by the escape of latch 112 fromthe catch 124) the reactive force on the latch plunger 86 ceases, thusrelieving the radially outward force on balls 82 and 84. The slopingengagement of the shoulder 92 on the curved surfaces of the balls 82 and84 will cause the balls to move inwardly until they clear the shoulder92, and then the complete plunger assembly 40 will move upwardly of thecasing under the bias of spring 70, carrying the pin 102 with it. Theupward motion of pin 102 (as drawn) together with the pull of thetension spring 118 will rotate bell crank counter-clockwise about pin102 to pull movable contact 148 away from stationary contacts 1'70 and172, thus breaking the electrical circuit through the circuit breaker.

FIG. 6 shows the parts in the intermediate position just afterunlatching because of current flow through the thermostat actuator 180.It will be noted that the latch 112 has become disengaged from its catch124, and that the spring 118 has thus had an opportunity to disengageimmediately the bridging contact 148 from the stationary contacts and172. The balls 32 and 84 have disengaged from the shoulder 92, and thelatch plunger has commenced its-upward motion, as has also the sleeve44.

Referring to FIG. 5, the parts are shown in the complete contacts-openposition. In this position, it will be noted that the parts have movedupwardly, and that because of this upward movement, the bell crank is sopositioned that the catch 124 and its latch 112 are now in position forengagement if the push button is shoved inwardly to close the contactsagain. S-hoving the push button 42 inwardly will cause the parts toreturn to the FIG. 1 position with the contacts closed. Of course, thelatch 112 will not engage the catch 124 unless the thermostat actuatorhas cooled down sufficiently to permit the slide 204 to move to theright enough to permit the biasing spring 126 to move the thermostatbimetal compensator 122 and the catch 124 also to the right.

That the device is trip-free will be seen by the following explanation:if the plunger 40' is held inwardly of the casing by externally appliedforce, and the thermostat actuator 180 moves to the left (as drawn) tomove the ambient compensating lever 122 to the left and thus free latch112 from catch 124, then, even though pin 102 is held stationary, thetension spring 118 will act on the leg 114 of the bell crank in order torotate the bell crank counter-clockwise to pull movable contact 148 fromthe stationary contacts 170 and 172.

In the event that the circuit breaker is exposed to a higher ambienttemperature than that at which it originally was calibrated, ambientcompensation takes place as follows: as has been described above, theambient compensating element 122 is made of thermostat metal, and itshigh expansion side is to the right as drawn and its low expansion sideis to the left. Upon heating due to the change in ambient temperature,the end of the bimetal compensating element will move to the leftapproximately the same distance that the end of the thermostat actuator180 moves to the left under the influence of the same ambienttemperature, and thus the relative spacing between these two respectiveends will remain constant. This means that in order to trip at a givenelectrical current, the end of thermostatic actuator 180 must alwaysmove the same distance in order to move the bimetal compensating lever122 a sufficient distance to trip the latch 112 from catch 124.

It is to be noted that the end of the compensating lever 122 can moveunder the influence of ambient temperature without substantiallyaffecting the position of catch 9 124. Thus, the invention has thefeature that the ambient compensating element is combined with thelatch, but can move for compensation without affecting the position ofthe catch in respect to the latch.

If desired, an arc shield 208 may be suitably provided betweenelectrical contacts 170 and 172 and suitable other partitions may beprovided to form are chambers for the contacts.

Referring now to FIG. 25, there is shown a fragmentary section of adevice similar to the FIG. 1 embodiment in all respects except that thestationary end of the spring 118 is, in this embodiment, fastened to astationary support 210. Support 210 may constitute a pin extendingacross the interior of the casing, the ends of the pin being held inrecesses suitably inserted in the inside walls of the casing. With thisconstruction, it will be noted that the assembly of the plunger, theball latch, the bell crank latch, the terminals, slide, thermostatactuating element, and compensating element can be placed in one of theclam shells, and then the spring 118 can be hooked over the end 210. Inorder to help on this it would be advantageous to make one of therecesses in the side wall a snug fit for one end of the pin so that thepin would be held erectly in alignment with the mating recess of theother clam shell when the latter is applied to contain the parts. Asindicated above, the FIG. 1 embodiment is the preferred embodimentbecause of its ease of assembly; however, the embodiment of FIG. 25 canbe used when desired.

In view of the above, it will be seen that the several objects of theinstant invention are achieved and other unique and advantageous resultsattained.

As many changes could be made in the above constructions withoutdeparting from the scope of the invention, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings, shall be interpreted as illustrative and not in a limitingsense, and it is also intended that the appended claims shall cover allsuch equivalent variations as come within the true spirit and scope ofthe invention.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. A switching device comprising a casing; a plunger mounted on saidcasing and movable into and out of said casing; at least one firstcontact mounted on said casing; a first thermostatic element mounted insaid casing and having one end free for movement; a second thermostaticelement mounted in said casing and having one end free for movement;slide means between the free ends of said first and second thermostaticelements, said slide means being adapted to transfer motion from thefree end of said first thermostatic element to the free end of saidsecond thermostatic element; a catch attached to said secondthermostatic element and movable therewith upon movement thereof by saidfirst thermostatic element; a first latch rotatably mounted at one endof said plunger and adapted to cooperate with said catch; a movablecontact carried by said first latch and movable thereby to engage anddisengage said first contact to make and break an electrical circuittherethrough upon movement of said first latch; a second latch engagingsaid plunger releasably to hold said plunger in position with said firstand movably contacts closed, said second latch being releasable topermit motion of said plunger toward a contact-open position when saidfirst latch is released from said catch; and a portion of said secondthermostatic element being movable under the influence of a change inambient temperature without disengaging said first latch and said catch.

2. The switching device of claim 1 in which said first latch is abell-crank one extremity thereof being adapted to engage said catch, andanother extremity of which is engaged by spring means resiliently androtatively biasing said crank about its pivot, and in which said movablecontact is resiliently mounted on said bell-crank.

3. The switching device of claim 1 in which said second thermostaticelement is a blade pivotally mounted at one end thereof in said casingwith the other end thereof being engageable by said slide; and saidcatch is an elongated metal member attached at one end to said bladeadjacent the pivoting end of the latter with the remaining length ofsaid member being free of said blade and having its free end positionedbetween the ends of said blade, whereby said blade can bend under theinfluence of heat without moving the free end of said catch.

4. A switching device comprising a casing; manually actuable meansmounted on said casing and movable with respect thereto; at least onefirst contact mounted on said casing; condition-responsive means mountedin said casing and having at least a portion thereof free for movement;a thermostatic element blade pivotably mounted at one end thereof insaid casing with the other end thereof being free for movement; motiontransfer means operatively coupling the movable portion of said firstcondition-responsive means and the movable end of said thermostaticblade; a catch operatively associated with said thermostatic blade andmoveable thereby upon movement of said first condition-responsive means;said catch embodying an elongated metal member attached at one endthereof to said thermostatic blade adjacent the pivoting end of thelatter but the remaining length of said member being free of said bladeand having its free end positioned between the ends of said blade sothat said blade can bend under the influence of heat without moving thefree end of said catch; a first latch operatively connected to saidmanually actuable means and adapted to cooperate with said catch; atleast one movable contact operable by said latch and adapted to engageand disengage said first contact to make and break an electrical circuittherethrough upon movement of said latch; a second latch engaging saidmanually actuable means releasably to hold the latter means in positionwith said first and movable contacts closed; said second latch beingreleasable to permit motion of said manually actuable means toward acontacts-open position when said first latch is released from saidcatch; said movable end of said thermostatic blade being movable in thesame direction as the movable portion of said first condition-responsivemeans under the influence of a change in condition of both of said firstcondition-responsive means and said thermostatic blade withoutdisengaging said first latch and said catch.

'5. A switching device comprising a casing; manually actuable meansmounted on said casing and movable with respect thereto; at least onefirst contact mounted in said casing; a first condition-responsive meansmounted in said casing and having at least a portion thereof free formovement; a second condition-responsive means mounted in said casing andhaving at least a portion thereof free for movement; coupling meansbetween the free portions of said first and second condition-responsivemeans for transferring motion from the free portion of one of saidcondition-responsive means to the free portion of the other of saidcondition-responsive means; a catch connected to said secondcondition-responsive means and movable therewith upon movement thereofby said first condition-responsive means; a bell-crank latch rotatablymounted on said manually actuable means and adapted to cooperate withsaid catch; at least one movable contact resiliently mounted on saidbell-crank for movement thereby to engage and disengage said firstcontact to make and break an electrical circuit therethrough uponturning movement of said bell-crank latch; a ball-clutch latch engagingsaid manually actuable means releasably to hold said latter means inposition with said stationary and movable contacts closed, saidball-clutch detaining said manually operable means from automaticrelease while force is exerted on said clutch but automaticallyreleasing said manually actuable means when said force is relieved bydisengagement of said catch from said latch; and a second portion ofsaid second condition-responsive means being movable under the influenceof a change in ambient temperature without disengaging said bell-cranklatch in said catch.

6. A switching device comprising a base, first contact means mounted onsaid base, manual actuating means mounted on said base for movementbetween first and second switch positions, means biasing said actuatingmeans to said first switch position, a first latch rotatably mounted onsaid actuating means for movement therewith between said first andsecond switch positions, second contact means carried by said firstlatch, a catch movably mounted on said base to normally engage saidfirst latch during movement of said actuating means into said secondswitch position for rotating said first latch to engage said secondcontact means with said first contact means, a second latch holding saidactuating means in said second position when said first latch is engagedwith said catch, said second latch being releasable by manual movementof said actuating means for permitting said actuating means to move tosaid first switch position to disengage said first and second contactmeans, and current-responsive means mounted for movement on said base tomove said catch out of engagement with said first latch for permittingsaid actuating means to move to said first switch position to disengagesaid first and second contact means.

7. A switching device comprising a base, first contact means mounted onsaid base, manual actuating means mounted on said base for movementbetween first and second switch positions, means biasing said actuatingmeans to said first position, a first latch rotatably mounted on saidactuating means for movement therewith between said first and secondswitch positions, second contact means carried by said first latch, athermostatic element blade pivotably mounted at one end on said base andhaving its opposite end free for movement, an elongated catch memberattached at one end to said thermostatic blade adjacent the pivoting endof said blade and having its opposite end positioned to normally engagesaid first latch during movement of said actuating means into saidsecond switch position for rotating said first latch to engage saidsecond contact means with said first contact means to close a circuit,means biasing said front latch to disengage said first and secondcontact means when said first latch is disengaged from said catch, asecond latch holding said actuating means in said second switch positionwhen said first latch is engaged with said catch, said second latchbeing releasable by manual movement of said actuating means forpermitting said actuating means to move to said first switch position todisengage said first and second contacts to open said circuit,current-responsive means interposed in said circuit and mounted formovement on said base in response to selected current in said circuit,and motion transfer means between said current-responsive means and saidfree end of said thermostatic blade to move said catch out of engagementwith said first latch in response to said selected current in saidcircuit for permitting said actuating means to move to said first switchposition to disengage said first and second contact.

8. A trip-free, ambient-compensated, switching device adapted forminiaturization comprising a base housing forming a generallyrectangular housing chamber, first contact means mounted in said housingchamber at one end thereof, manual actuating means mounted at anopposite end of said housing chamber for movement between first andsecond switch positions, means biasing said actuating means to saidfirst switch position, a first latch rotatably mounted on said actuatingmeans within said chamber for movement with said actuating means betweensaid first and said second switch positions, second contact meanscarried by said first latch, a thermostatic element blade having one endpivotably mounted within said housing adjacent said one end of saidhousing, said blade extending along one side of said housing chamber andhaving its opposite end free for movement, an elongated catch memberattached at one end to said thermostatic blade adjacent the pivoting endof said blade and having its opposite end positioned to normally engagesaid first latch during movement of said actuating means into saidsecond switch position for rotating said first latch to engage saidsecond contact means with said first contact to close a circuit, meansbiasing said first latch for rotation to disengage said first and secondcontact means when said first latch and catch are disengaged, a secondlatch holding said actuating means in said second switch position whensaid first latch is engaged with said catch, said second latch beingreleasable by manual movement of said actuating means for permittingsaid actuating means to move to said first switch position to disengagesaid first and second contact to open said circuit, a secondthermostatic element blade having one end mounted within said housingadjacent said one end of said housing, said blade extending along theopposite side of said housing and having its opposite end free formovement, said second blade being interposed within said circuit formovement in response to selected current in said circuit, andmotiontransfer means extending across said opposite end of said housingchamber between said free ends of said thermostatic element blade formovement with said blades independent of said catch in response tochange in ambient temperature, said motion transfer means moving saidcatch out of engagement with said first latch with movement of saidsecond thermostatic element blade in response to said selected currentin said circuit for permitting said actuating means to move to saidfirst switch position to disengage said first and second contact meansto open said circuit.

9. A switching device as set forth in claim 8 having a hollow, generallycylindrical neck attached to said housing at said opposite end thereoffor mounting said housing, said second latch being enclosed within saidmounting neck.

10. A switching device as set forth in claim 8 wherein said motiontransfer means comprises a slide apertured to permit movement of saidactuating means therethrough.

References Cited UNITED STATES PATENTS 2,666,828 6/ 1954 Dyer et al200-116 2,318,279 5/1943 ASchWanden 2O01 16.1 2,908,786 10/ 1959Schleicher ZOO-116.1 3,142,732 7/ 1964 Clarke et al. ZOO-116.1

FOREIGN PATENTS 242,726 11/ 1925 Great Britain.

BERNARD A. GILHEANY, Primary Examiner.

H. B. GILSON, Assistant Examiner.

